Preparation and characterization of Cd 1−xFe xSe single crystals

Abstract

The limit of substitution of iron for cadmium in CdSe was determined by x-ray diffraction of polycrystalline samples to be 11.5 ± 1 mole percent. This degree of substitution of Fe(II) on a tetrahedral site is of interest since Fe(II) usually prefers octahedral coordination. The presence of tetrahedral Fe(II) in this system provides a new class of semimagnetic semiconductors. Single crystals of Cd 1−xFe xSe were grown by CVT and by a modified Bridgman method. The magnetic susceptibility of crystals grown by both methods displayed field-independent behavior, indicating the absence of any magnetic Fe/Se phase. Measurements of susceptibility as a function of temperature showed Curie-Weiss behavior with net antiferromagnetic interactions. Bridgman-grown crystals have room temperature resistivities at least 10 3 ohm-cm higher than that of the CVT grown crystals (1700 ohm-cm). The iron concentration of Bridgman-grown crystals was homogeneous in a radial direction, but showed 0.5 – 0.8 mole percent change in iron concentration along the length of the boule.